1. Field of the Invention
This invention is directed to a simplified process of direct interchange for converting calcium derivatives of phenol sulfides to transition metal containing derivatives of phenol sulfides. Such compounds are useful as lubricant oil additives.
2. Discussion of the Prior Art
Calcium derivatives of phenol sulfides are known, are extensively used and are highly useful in the lubricating art. Transition metal derivatives of precursor phenol sulfides have been disclosed in for example U.S. Pat. Nos. 2,409,687 and 2,362,293. Conversion of phenol sulfides to products containing both transition metals and alkaline earth metals by reaction with mixtures of basic salts of those metals have also been disclosed, see the aforementioned U.S. Pat. No. 2,362,293. However, it is believed that the method of preparing transition metal-containing calcium derivatives of phenol sulfides by direct interchange reaction as disclosed herein is not known or disclosed in the prior art. The prior use of mixtures of transition metal basic salts and alkaline earth metal basic salts differs from the process of this invention, inter alia, in that in the prior art the inclusion of the transition metal is random and substantially uncontrolled; the amount of transition metal included is highly variable and significant amounts of unreacted costly transition metal salts are thus wasted or rendered difficult and expensive to recover. Furthermore, the composition of such products is so different from the products of this invention that they have an inability to achieve or carefully control that desired and most effective balance between antioxidation activity, lubricant detergent properties and reserve alkalinity which is readily achieved by said products of the present invention.